Method for producing hollow bodies in centrifugal casting molds rotatable about the vertical axis



y 3, 1941- F. BARTSCHERER 2.248693 METHOD FOR PRODUCING HOLLOW BODIES INCENTRIFUGAL CASTING MOLDS ROTATABLE ABOUT THE VERTICAL AXIS Filed March30, 1938 Patented July 8, 1941 UNITED STATES PATENT OFFICE FranzEartscherer, Duisburg-Hamborn, Germany Application March 30, 1938,Serial No. 199,000 In Germany April 2, 1937 1 Claim.

Hollow bodies, especially those of cast steel, which are produced incentrifugal casting molds rotating about their vertical axis have, ifthe centrifuging is carried out in the correct manner, thin wallthickness and dense wall cross sections without piping or segregation.However, in the case of hollow bodies with thick walls traces of pipingpores and segregations often occur on the inner surface, especially inthe lower half of the body. In order to obtain a uniformly good andclean surface also in hollow bodies with thick walls, all piping andsegregation must be avoided. Piping and segregation is due to that thesolidifying of the material in the solidifying hollow cylinderprogresses more quickly from the top than from the bottom surface. Theformation of piping pores and segregations is favoured particularly inthe lower half of the block where the material remains liquid longest.The wall of the hollow body, however, is mostly clean in the upper zoneand also a distance above the bottom plate especially when a refractorybottom. plate and a refractory mold cover are employed during thecasting of the hollow body.

For regulating the solidifying process of hollow bodies which are madein centrifugal casting molds rotatable about their vertical axis, it isknown to additionally cool rapidly the inner wall of the hollow bodyduring the solidification.

The invention is based on the recognition of the fact that it issuflicient to additionally cool chill.

rapidly only the lower portion of the solidifying I inner wall of thehollow body. The artificial cooling can be effected by blowing oncompressed air, if desired mixed with steam or water, or some othersuitable cooling medium or by introducing a cooling body adapted to theinner side of the An apparatus for carrying out the process isillustrated by way of example in vertical section in the accompanyingdrawing.

Referring more particularly to the drawing there is provided a chill 2arranged vertically on the centrifuging device I and in which the lustsolidifying hollow body 3 of centrifuged metal is contained. Theformation of pipings and segregation during the solidifying of thehollow cylinder wall is prevented by the additional accelerated coolingof the lower portion of the inner wall by a cooling medium, such ascompressed air, steam, or water mist, which is projected onto the innerwall of the hollow cylinder 3 by a cool: ing pipe lshiftable in theaxial direction of the Only the cooling of the lower portion 5 of thehollow cylinder is accelerated thereby. An additional simultaneousheating of the upper portion of the inner wall is effected by a heatingdevice 8 which directs a sheet of hot gas of combustible gasesthereagainst.

The great advantage of the method according to the invention consists inthat not only the outmolding of good hollow bodies is increased in thecentrifuging process but also and chiefiy in that the quality of theinner side of the wall is considerably improved. The clean inner surfaceof the hollow body thus produced enables the subsequent machiningexpenses in the case of finished machining of the cylinder to be reducedto a miniimiimdso that a great economical saving is oba ne 1 The methodaccording to the invention-is not Q restricted to the production ofhollow bodies by centrifuging of carbon steel, but it can beadvantageously applied to alloyed steels and metal alloys and also tothe production of hollow compoimtli castings in the centrifuging method.

A method for the production of heavy hollow

